Preparation of isopropyl benzene hydrocarbons



benzene hydrocarbon occurs.

PREPARATION OF ISOPROPYL BENZENE HYDROCARBONS Gordon E. Langiois, El Cerrito, Califi, assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Application June 25, 1953, Serial No. 364,219

5 Claims. (Cl. 260671) This invention relates to an improved process for the preparation of isopropyl benzene hydrocarbons. More particularly, the invention has to do with the prepara- The aforesaid isopropyl benzene hydrocarbons, especially cumene, are useful as additives in, or as constituents of, aviation gasoline. In commercial practice, the

right, having engine perrormance properties comparable i with those of cumene.

Broadly, the invention is predicated on the discovery aforementioned isopropyl of the More particularly, alkylation temperatures fall between about 300 F. and 400 F., while the concentration of the phosphoric acid catalyst employed during reaction resides within about the range of 96% to 104%, based on orthophosphoric acid, and preferably between about 99% and 101%, based on orthophosphoric acid. This concentration is controlled by the amount of water in the feed, including propene and benzene hydrocarbon, during reaction. As will occur to those skilled in the art, the amount of water required in the feed to maintain a given acid concentration will depend on the temperature, pressure, composition of the feed, and fraction of the reaction miX vaporized. The amount of water added is such that the partial pressure of water in the vapor phase is equal to the vapor pressure of water of the particular conresult of which substantially improved utilization 2,713,600 Patented July 19, 1955 desired at the temperature under Thus, at an average temperature of 350 centration of acid consideration.

result in an acid concentration of 96%, 0.07% water and about 0.013% water, resulting, respectively, in acid concentrations of 100% and 104%.

The type of catalyst contemplated by the invention is not critical. In addition to the bulk liquid phosphoric acid catalyst, suitable catalyst material is the solid phosphoric acid type prepared by impregnating a diatomaceous kieselguhr, followed with about Patents Nos. 2,135,793 and 2,186,021; and the metal posed on crushed quartz particles of 28*35 mesh.

of the invention, tabulated below was pumped into the top of a reactor comprising a 2-inch by IO-foot tube passing downflow therethrough. The tube was filled approximately one-half full, about 3,000 cc.

metered, sampled, and diswere pumped to a topping still, a 3-inch by 6-foot packed column operated at atmospheric pressure. From the topping still recycle benzene was taken overhead and passed into calibrated feed vessels from which it was pumped back to the reproximately constant. Total benzene inventory within the plant, including the feed vessels, reactor, and stills was such that it made a complete cycle through the plant every two to three hours. The topping still bottoms were Withdrawn and fractionated batchwise to separate the isopropyl benzene hydrocarbon.

TABLE I Efiect of temperature and acid concentration on benzene utilization Run Number 14-1 M 6 14-16 14*20 Reaction Conditions:

Catal st 3 Average Temperature, F 393 301 354 475 Pressure, p. s. i. g 250 250 250 250 Feed Rates, Liq. V./V./Hr.:

Ca fraction 0.73 0. 57 0.73 0.74

Benzene 1. 23 0. 95 1. 27 1. 25 Benzene-Propene Mol Rat 5. 5.0 5. 2 5. 2 Water in Feed, Wt Percent... 0.005 0.005 0. 076 1. ()9 Acid. Concentration, Percent B31304. 106 106 100 100 Liquid Product, Wt. Percent:

Benzene 74. 0 75. 5 76. 7 77.0

Polymer- 0. 30 0. 55 0. 52 0. 45

Alkylate 25. 7 23. 0 22. 8 22. 5 Alkylate Composition, Mol Percent:

Ethyl Benzene 0.44 0. 47 0.45 0.47

Cume e 90. 75 90. 60 94. 77 90. 67

Butyl Benzene. 2. 40 2. 49 2. 40 2. 43

Amyl Benzene- 0. 33 0. 33 0. 33 0.32

Dipropyl Benzen 6. 08 6.11 2.05 6.11 Benzene Utilization 93. 8 93. 7 97. 7 93. 7 Propane Utilization 9 85. 4 82. 7 89. 9 83. 5

1 Mols eumeneXlOO Mols cumene+mols dipropyl benzene 1 Mols cumeneXiOO Mols propene reacting B H PO; on 2835 mesh crushed quartz.

Inspection of Table I reveals that in order to obtain the highest benzene utilization the simultaneous observance of the two conditions of temperature and acid concentration must be made. Thus, in run number l4-l, a benzene utilization of 93.8% was obtained. The acid concentration in the run was 106%, that is, beyond the tolerable maximum of 104%, although the temperature of 393 was well within the range of 300-400 F. Lowering the temperature to about 300 F., while maintaining the acid concentration of 106%, run 146, did not improve benzene utilization. It will be noted, however, that good benzene utilization was had in run number 14-16. Here the temperature was 354 F., and the acid concentration 100%, the temperature and acid concentration falling within suitable ranges. However, increasing the temperature decreases benzene utilization as shown in run number 14-20 even though a low acid concentration is maintained.

Tabulated below are operating conditions and results of runs in the preparation of cymene.

TABLE II Combined efiect of temperature and acid concentration on toluene utilization Run Number Catalyst Temperature, Pressure, p. s. i. Total Feed Rates, L .Iv./l1r Feed Composition, Wt. Percent:

Propane Toluene Toluene-Propene Mol Ratio Composition of Alkylate, Wt. Peree a: and more co a: CD wrocoo ammo: regs Cymene Higher boiling materia Toluene Utilization Acid Concentration, percent.

1 Solid phosphoric acid.

Toluene was alkylated with propene, to produce cymene by the procedure utilized in obtaining the data of Table I, except that the toluene was not recycled under the above conditions.

It will be noted that substantially greater toluene utilization (96.5%) occurs with low acid concentration and low temperature, run 1, as compared with that of run 2, (92.3%), wherein high acid concentration and high temperature were employed.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In the process of preparing an hydrocarbon by alkylating a benzene hydrocarbon having a molecular weight not exceeding that of xylene with propene, the improvement of effecting greater utilization of the benzene hydrocarbon,

isopropyl aromatic which comprises reacting the benzene hydrocarbon with propene at a pressure in the range of from about 200 to 1800 p. s. i. g. and at a temperature of at least about 300 F. but not exceeding about 400 F. in the presence of a liquid non-adsorbed phosphoric acid catalyst of a concentration of at least about 96% but not exceeding 104%, based on orthophosphoric acid.

2. Improvement substantially as described in claim 1, wherein the phosphoric acid catalyst is disposed as a film on crushed quartz of 28 to 35 mesh particles.

3. Improvement substantially as described in claim 1, wherein the acid concentration is about 99% to 101%, based on orthophosphoric acid.

4. Improvement substantially as described in claim 1, wherein the benzene hydrocarbon reacting with the propene is present in a mol ratio of about 3 to about 5 mole of benzene hydrocarbon per mol of propene.

5. Improvement substantially as described in claim 1, wherein alkylation pressures range from about 200 to 500 p. s. i. g.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN THE PROCESS OF PREPARING AN ISOPROPYL AROMATIC HYDROCARBON BY ALKYLATING A BENZENE HYDROCARBON HAVING A MOLECULAR WEIGHT NOT EXCEEDING THAT OF XYLENE WITH PROPENE, THE IMPROVEMENT OF EFFECTING GREATER UTILIZATION OF THE BENZENE HYDROCARBON, WHICH COMPRISES REACTING THE BENZENE HYDROCARBON WITH PROPENE AT A PRESSURE IN THE RANGE OF FROM ABOUT 200 TO 1800 P. S. I. G. AND AT A TEMPERATURE OF AT LEAST ABOUT 300* F. BUT NOT EXCEEDING ABOUT 400* F. IN THE PRESENCE OF A LIQUID NON-ADSORBED PHOSPHORIC ACID CATALYST OF A CONCENTRATION OF AT LEAST ABOUT 96% BUT NOT EXCEEDING 104%, BASED ON ORTHOPHOSPHORIC ACID. 